a pure sample as a standard. New peptide adducts formed by AL-II have been isolated by HPLC using a fluorescence detector and analyzed by MALDI mass spectrometry. A brief report of each of these advances is found in the Progress Report/Preliminary Studies section. Finally, Dr. Iden, seeking to improve access to state-of-the-art mass spectrometry techniques, submitted a proposal for a new triple quadrupole mass spectrometer system to the NIH National Center for Research Resources. Review by the Center for Scientific Review Special Emphasis Panel in July, 2006 was highly favorable and a priority score of 170 was assigned to the proposal. Council is scheduled to meet in October, 2006. If this instrument is acquired in the Spring, 2007, as scheduled, levels of sensitivity for quantitative detection of DNA and protein adducts will be increased by a factor of ten over that attained by our current triple quadrupole instrumentation. A. Specific Aims Oligodeoxynucleotide synthesis and chemical analysis performed by the Core Facility provides fundamental support for all Program research. The Core will provide modified and normal oligomers to all investigators. DNA synthesis personnel will work closely with synthetic chemists to test new, modified deoxynucleosides phosphoramidites and incorporate them into DNA oligomers. We will refine our quantitative mass spectrometer methods and proteomics capabilities and focus on the development of sensitive, new techniques to identify DNA and protein adducts formed by the aristolochic acids (AAs) and their metabolites. The specific aims of the Core Facility are: 1. Toprepare